Combining Homotopy Methods and Numerical Optimal Control to Solve Motion Planning Problems

This paper presents a systematic approach for computing local solutions to motion planning problems in non-convex environments using numerical optimal control techniques. It extends the range of use of state-of-the-art numerical optimal control tools to problem classes where these tools have previously not been applicable. Today these problems are typically solved using motion planners based on randomized or graph search. The general principle is to define a homotopy that perturbs, or preferably relaxes, the original problem to an easily solved problem. By combining a Sequential Quadratic Programming (SQP) method with a homotopy approach that gradually transforms the problem from a relaxed one to the original one, practically relevant locally optimal solutions to the motion planning problem can be computed. The approach is demonstrated in motion planning problems in challenging 2D and 3D environments, where the presented method significantly outperforms a state-of-the-art open-source optimizing sampled-based planner commonly used as benchmark

A Penny Saved is a Penny Learned!

This article discusses modifying a specific activity so that it promotes scientific inquiry, cooperative learning, accurate and explicit nature of science understanding, and appropriate assessment. It features a brief description of the original cookbook activity and a subsequent adaptation to create an inquiry-based lesson. The activity uses ordinary pennies to teach fundamental concepts such as density and indirect measurements. Extension activities for chemistry students could feature chemical reactions and metal activities. This article promotes National Science Education Content Standards A, B, and G, and Iowa Teaching Standards 1, 2, 3, 4, 6, and 8

Non-fatal self-harm in Scottish military veterans: a retrospective cohort study of 57,000 veterans and 173,000 matched non-veterans

Purpose: Although suicide risk in veterans has been widely studied, there is little information on the risk of non-fatal self-harm in this population. We used data from the Scottish Veterans Health Study to conduct an epidemiological analysis of self-harm in veterans, in comparison with people who have never served. Methods: We conducted a retrospective, 30-year cohort study of 56,205 veterans born 1945–1985, and 172,741 people with no record of military service, and used Cox proportional hazard models to examine the association between veteran status and cumulative risk of non-fatal self-harm, overall and stratified by birth cohort, sex and length of service. We also examined mental and physical comorbidities, and association of suicide with prior self-harm. Results: There were 1620 (2.90%) first episodes of self-harm in veterans, compared with 4212 (2.45%) in non-veterans. The difference was statistically significant overall (unadjusted HR 1.27, 95% CI 1.21–1.35, p < 0.001). The risk was highest in the oldest veterans, and in the early service leavers who failed to complete initial training (unadjusted HR 1.69, 95% CI 1.50–1.91, p < 0.001). The risk reduced with longer service and in the intermediate birth cohorts but has increased again in the youngest cohort. Conclusions: The highest risk of non-fatal self-harm was in veterans with the shortest service, especially those who did not complete training or minimum engagement, and in the oldest birth cohorts, whilst those who had served the longest were at reduced risk. The risk has increased again in the youngest veterans, and further study of this subgroup is indicated

Lymphohaematopoietic malignancies in Scottish military veterans: Retrospective cohort study of 57,000 veterans and 173,000 non-veterans

Background: Lymphohaematopoietic malignancies are common in the general population. There have been concerns that military service may be associated with increased risk as a result of occupational exposures. To date, few studies have demonstrated an increased risk, although a disability pension is payable to veterans who were present at nuclear tests and who develop leukaemia (other than chronic lymphocytic leukaemia). The aim of the study was to utilise data from the Scottish Veterans Health Study to examine the risk of lymphohaematopoietic malignancy following military service in a large national cohort of veterans. Methods: Retrospective cohort study of 57,000 veterans and 173,000 non-veterans born between 1945 and 1985 matched for age, sex and area of residence, adjusted for areal deprivation and followed up for up to 30 years, using Cox proportional hazard models to compare the risk of lymphohaematopoietic malignancy overall, by diagnosis and by sex and birth cohort. Results: We found no statistically significant difference in risk between veterans and non-veterans either for all leukaemias (Cox proportional hazard ratio 1.03, 95% confidence intervals 0.84–1.27, p = 0.773), Hodgkin lymphoma (hazard ratio 1.19, 95% confidence intervals 0.87–1.61, p = 0.272) or for non-Hodgkin lymphoma (hazard ratio 0.86, 95% confidence intervals 0.71–1.04, p = 0.110). Conclusion: Our findings provide reassurance that service in the UK Armed Forces is not associated with increased risk of lymphohaematopoietic malignancy

The effects of two secondary science teacher education program structures on teachers\u27 habits of mind and action

This study investigated the effects of the Iowa State University Secondary Science Teacher Education Program (ISU SSTEP) on the educational goals and habits of mind exhibited by its graduates. Ten teachers from ISU SSTEP participated in the study---five from the former program featuring one semester of science teaching methods, five from the current program featuring three semesters of science teaching methods (four for the graduate certification consortium). A naturalistic inquiry research approach included the following methods used with each teacher: three classroom observations, classroom artifact analysis, teacher questionnaires and semi-structured interviews, and questionnaires for students about perceived emphasis of educational goals.;Evidence exists that graduates from the current ISU SSTEP format exhibited a closer match to the educational goals promoted, modeled, and advocated by the science teaching methods faculty. Graduates from the current ISU SSTEP also exhibited a closer match to the habits of mind---understanding, action, reflection, action plan for improvement---promoted and modeled by the program. This study has implications for other secondary science teacher education programs, particularly increasing the number of science teaching methods courses; teaching meaningful content of both concepts and skills through a research-based framework; modeling the appropriate teacher behaviors, strategies, habits, and goal promotion by methods instructors; and addressing issues of institutional constraints experienced by future teachers

Cyanogenesis in Dermatocarpon miniatum (L.) Mann.

The lichen species Dermatocarpon miniatum (L.) Mann. was found to be cyanogenic. This umbilicate lichen, which is common on limestone and sandstone outcrops throughout the United States, is the first lichen to be reported as cyanogenic. This species were examined for cyanogenesis using population from within the confines of Kankakee River State Park, Kankakee and Will Counties, Illinois. Of the nine populations examined six of the population (testing 30 to 150 individuals in each population) were 100% strongly cyanogenic. In the three remaining population cyanogenesis ranged from 67% to 97%. In addition D. miniatum, two other lichen species also were found to be occasional cyanogenic. Both Dermatocarpon fluviatile (G. Web.) Th. Fr. and Usnea cavernosa Tuck. gave slightly positive tests for cyanide. The isolation of the cyanogenic compound in D. miniatum was attempted. A cyanogenic extract from this species was purified using paper chromatography. This extract was analyzed using Nuclear Magnetic Resonance techniques (NMR). The results of this analysis shows a prominent sugar peak between 3.0-4.0 on the NMR spectrum which fits well with the idea that the compound responsible is a cyanogenic glycoside. A mass spectrum analysis was also attempted on the sample, but gave little information concerning the compounds molecular weight. This was probably due to impurities in the sample

Prospective Teachers’ Perceptions of Influential Teacher Qualities

While much has been written regarding elements of “good” teachers, little exists with respect to qualities of influential teachers. Prospective science teachers (N = 98) completed a survey identifying and describing influential teachers in their own lives. In addition to demographic data, qualitative content analysis of narratives excavated common themes. The seven most frequent attributes of influential teachers were passion, rapport, pedagogy, time, high expectations, fun, and helpful. Implications for teacher education and research include synergistic combinations of these traits, alignment with literature on effective teaching, development of professional dispositions, and more